title: Noninvasive evaluation of collateral blood flow through circle of Willis in cervical carotid stenosis using selective magnetic resonance angiography.
abstract: BACKGROUND
  Preoperative assessment of intracranial collateral circulation is helpful in predicting cerebral ischemia during surgical procedures for cervical internal carotid artery (ICA) stenosis. However, magnetic resonance angiography (MRA) and other less-invasive techniques cannot evaluate collateral blood flow because these techniques are nonselective. Hence, by using a newly developed selective MRA technique, we attempted to visualize collaterals via the circle of Willis in patients with ICA stenosis.
  
  
  METHODS
  Twelve patients who underwent carotid endarterectomy were prospectively examined with a 1.5-T MR scanner. Both selective and nonselective MRA were obtained using a 3-dimensional time-of-flight technique, with or without a cylindrical saturation pulse that suppresses the flow signal from the region of the target ICA. Maximum intensity projection MRA images were generated and compared with digital subtraction angiography (DSA) images.
  
  
  RESULTS
  In all patients, the distal flow signal of the ipsilateral ICA was completely suppressed on selective MRA compared with nonselective MRA. In addition, collateral blood flow through the anterior and posterior communicating arteries was visualized in 5 and 2 patients, respectively. These findings corresponded well with the DSA imaging.
  
  
  CONCLUSIONS
  Selective MRA techniques can readily suppress signals from the distal blood flow of the target artery and visualize the presence of collateral flows through the circle of Willis in patients with cervical ICA stenosis.
authors.affiliation: Division of Ultrahigh Field MRI, Institute for Biomedical Sciences, Iwate Medical University, Yahaba, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Ito
authors.affiliation: Division of Ultrahigh Field MRI, Institute for Biomedical Sciences, Iwate Medical University, Yahaba, Japan. Electronic address: masasaki@iwate-med.ac.jp.
authors.forename: Makoto
authors.initials: M
authors.lastname: Sasaki
authors.affiliation: Department of Neurosurgery, Iwate Medical University, Morioka, Japan.
authors.forename: Masakazu
authors.initials: M
authors.lastname: Kobayashi
authors.affiliation: Department of Neurosurgery, Iwate Medical University, Morioka, Japan.
authors.forename: Kuniaki
authors.initials: K
authors.lastname: Ogasawara
authors.affiliation: Hitachi Medical Corporation, Tokyo, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Nishihara
authors.affiliation: Hitachi Medical Corporation, Tokyo, Japan.
authors.forename: Tetsuhiko
authors.initials: T
authors.lastname: Takahashi
authors.affiliation: Division of Ultrahigh Field MRI, Institute for Biomedical Sciences, Iwate Medical University, Yahaba, Japan.
authors.forename: Tatsunori
authors.initials: T
authors.lastname: Natori
authors.affiliation: Division of Ultrahigh Field MRI, Institute for Biomedical Sciences, Iwate Medical University, Yahaba, Japan.
authors.forename: Ikuko
authors.initials: I
authors.lastname: Uwano
authors.affiliation: Division of Ultrahigh Field MRI, Institute for Biomedical Sciences, Iwate Medical University, Yahaba, Japan.
authors.forename: Fumio
authors.initials: F
authors.lastname: Yamashita
authors.affiliation: Division of Ultrahigh Field MRI, Institute for Biomedical Sciences, Iwate Medical University, Yahaba, Japan.
authors.forename: Kohsuke
authors.initials: K
authors.lastname: Kudo
mesh_terms: D000368:Aged; D015901:Angiography, Digital Subtraction; D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery; D016893:Carotid Stenosis / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery; D002533:Cerebral Angiography / Q000379:methods*; D002560:Cerebrovascular Circulation; D002941:Circle of Willis / Q000000981:diagnostic imaging / Q000503:physiopathology*; D003097:Collateral Circulation; D016894:Endarterectomy, Carotid; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D055420:Perfusion Imaging / Q000379:methods*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012039:Regional Blood Flow; D012720:Severity of Illness Index
keywords: Magnetic resonance angiography; carotid endarterectomy; cervical carotid stenosis; circle of Willis; collateral blood flow